The present invention is related to methods for fabricating multi-channel array optical device to achieve a uniform interleaving between different wavelengths and having precise wavelengths by accomplishing wavelengths adjustment and the forming of mirror layers simultaneously through a multi-layer binary mask and a selective oxidization process. The present invention is especially useful for fabricating multi-channel array optical devices including multi-channel passive filters and multi-channel surface emitting laser arrays.
Previous methods for obtaining uniformly interleaved wavelengths between different wavelengths and for having precise wavelengths employed controlling the thickness through the etching after inserting a phase tuning layer at resonant structure to obtain the desired channel wavelengths. Alternatively, a way of controlling the growing structure thickness was used to select resonant wavelengths by giving a growing temperature gradient with respect to patterns, which were previously patterned at the bottom of the substrate when the device structure is growing.
However, disadvantages of the mentioned previous techniques include complexity due to the processes of forming material layers to vary the wavelengths and, are also complicated demanding additional upper mirror layers, and material layers to adjust the wavelengths.
The disclosed embodiments of the invention provide fabrication methods for multi-channel array optical devices with a uniform wavelength spacing and a precise wavelength as well as simplified processes by accomplishing wavelengths adjustment and by forming mirror layers simultaneously through a multi-layer binary mask and a selective oxidization process.
A method for fabricating a multi-channel array optical device is provided. The method includes the following: Forming a plurality of semiconductor mirror layers on a semiconductor substrate; forming an oxidization protective layer on the plurality of semiconductor mirror layers; selectively removing the oxidization protective layer by using a binary mask to expose the semiconductor mirror layer, which will adjust a wavelength; and oxidizing the exposed semiconductor mirror layer.
Preferably, the semiconductor mirror layer is repetitively stacked in the order of a layer of stable to oxidization, a layer of adjustable oxidization speed, a layer of sensitive to oxidization, a layer of adjustable oxidization speed, and a layer of stable to oxidization.
Preferably, the layer of stable to oxidization, the layer of adjustable oxidization speed, and the layer of sensitive to oxidization are GaAs, AlGaAs and AlAs, respectively.
Preferably, the AlGaAs layer is adjusted an oxidization speed in accordance with an amount of Al.
Preferably, the oxidization protective layer is silicon nitride.
Preferably, the oxidization process is wet oxidization under the H2O and N2 ambient with the temperature of 400xc2x0 C. and 450xc2x0 C.
A method for fabricating a multi-channel array optical device is provided. The method includes: Forming a plurality of semiconductor mirror layers on a semiconductor substrate; forming an oxidization protective layer on the plurality of semiconductor mirror layers; selectively removing the oxidization protective layer by using a binary mask to expose the semiconductor mirror layer, which will adjust a wavelength; oxidizing the exposed semiconductor mirror layer; removing the remained oxidization protective layer; and repetitively performing the second step to the fifth steps to adjust the wavelength of the semiconductor mirror layers by using binary masks that have different light exposure widths.